Question

Find an explicit formula for the arithmetic sequence 12, 5, -2, -9,...

Answer 1

Answer:

an = 12 -7(n-1)

an = 19-7n

Step-by-step explanation:

The explicit formula for an arithmetic sequence is

an = a1 +d(n-1) where a1 is the first term and d is the common difference

a1 =12

We find d by taking the second term and subtracting the first term

d = 5-12

d = -7

an = 12 -7(n-1)

We can simplify this

an = 12 -7n+7

an = 19-7n